Reduced engine deposits from dispersant treated with cobalt

ABSTRACT

The invention provides a lubricating composition containing an oil of lubricating viscosity and a dispersant treated with cobalt reagent. The invention further relates to methods of lubricating an internal combustion engine by supplying the described lubricating composition to the internal combustion engine. The invention further relates to the use of a dispersant treated with cobalt to reduce deposits on the inner surfaces of engine components.

FIELD OF INVENTION

The invention provides a lubricating composition containing a dispersant treated with cobalt to reduce the formation of high temperature insoluble solids formed during exposure of the composition to heat. The invention further relates to the use of the lubricating composition in an internal combustion engine. The invention further relates to a method of reducing insoluble deposits in an engine using said dispersant treated with cobalt and said lubricating composition.

BACKGROUND OF THE INVENTION

It is known that lubricants become less effective during their use due to exposure to the operating conditions of the device they are used in, including exposure to heat, oxygen, and partial combustion by-products generated by the operation of the device. For example, engine oil becomes less effective during its use, in part due to exposure of the oil to acidic and pro-oxidant by-products. These oxidized and acidic hydrocarbons of the lubricant can then go on to cause corrosion, wear and deposit problems.

Modern engine designs tend to incorporate smaller sump volumes coupled with higher operating temperatures than ever before. These design specifications lead to greater oxidative stress on the lubricant and increased propensity to form high temperature deposits on key zones such as the piston ring zone.

Given the continual demands placed on the lubricant by the modern engine designs mentioned above, modern engine testing is necessarily becoming more severe. For instance, the industry standard high temperature deposit test (Sequence IIIG) is a very severe piston cleanliness test with high sump temperatures and high load. There are a variety of bench tests that seek to simulate the deposit forming tendencies of lubricating oils in this and other engine tests including the Komatsu hot tube test (KHT). The procedure calls for circulating an oil through a hot glass tube (232-320° C. and more typically 270-290° C.) for a specified period of time. At the end of test, the tube is rated visually for deposits with a rating of 10 being a perfectly clear tube and 0 being a black tube. The test gauges the innate tendency of the lubricant to form deposits in the absence of combustion processes.

Current and proposed specifications for crankcase lubricants, such as GF-5 for passenger car motor oils, and PC-10 for heavy duty diesel engines specify increasingly stringent standards or limits to meet government specifications. Of particular concern are sulfur and phosphorus limits. Sulfur and phosphorus from the lubricant can end up in the catalytic converter. It is widely believed that lowering these limits in lubricants may have a serious impact on engine performance, engine wear, and oxidation of engine oils. This is because historically a major contributor to phosphorus content in engine oils has been zinc dialkyldithiophosphate (ZDP), and ZDP has long been used to impart antiwear and antioxidancy performance to engine oils. Thus, as reduced amounts of ZDP are anticipated in engine oils, there is a need for alternatives to impart protection against deterioration in one or more of the properties of engine performance, engine wear, and oxidation of engine oils. Such improved protection is desirable whether or not ZDP and related materials are included in the lubricant. Desirable lubricants may be low in one or more of phosphorus and sulfur.

There is a need for dual function additives that provide engine deposit control at high operating temperatures along with one of the conventional functions of an engine oil additives (such as dispersing of soot and sludge). In addition, it is desirable if this dual function additive also can function with low levels of conventional antioxidants and/or low levels of metal or sulfur containing additives in the lubricant.

SUMMARY OF THE INVENTION

The present invention relates to cobalt modified dispersants. These cobalt modified dispersants tend to minimize deposits formed as a result of oil insoluble oxidation products on the walls of glass tubes and engine components. These cobalt modified dispersants also increase the oxidation induction times of the formulated lubricant in tests like the SAE CECL85.

It has now been discovered that the presence of cobalt, supplied for instance in the form of a reaction product of aminic (also known as ashless) dispersants and cobalt compounds, such as Co⁺² or Co⁺³ provides a beneficial effect on one or more of the above properties. In particular, such materials as cobalt PIB-succinimide dispersants impart a beneficial effect in one or more of the Komatsu Hot Tube deposits screen test (KHT).

The cobalt can be supplied as a Co-modified dispersant, such as a succinimide dispersant, Mannich base, or hydrocarbyl based polymer dispersants. Such materials may be prepared by forming a cobalt mixed anhydride between a cobalt alkoxide, chloride, carbonate, hydroxide, acetate, etc. and a hydrocarbyl-substituted succinic anhydride, such as an alkenyl- or alkyl-succinic anhydride. The resulting cobalt-succinate intermediate may be used directly or it may be reacted with any of a number of materials, such as (a) a polyamine-based succinimide/amide dispersant having free, condensable —NH functionality; (b) the components of a polyamine-based succinimide/amide dispersant, i.e., an alkenyl- or alkyl-succinic anhydride and a polyamine, (c) a hydroxy-containing polyester dispersant prepared by the reaction of a substituted succinic anhydride with a polyol, aminoalcohol, polyamine, or mixtures thereof. Alternatively, the cobalt-succinate intermediate may be reacted with other agents such as alcohols, aminoalcohols, ether alcohols, polyether alcohols or polyols, or fatty acids, and the product thereof either used directly to impart cobalt to a lubricant, or else further reacted with the succinic dispersants as described above. As an example of a dispersant post treated with metal, 1 part (by mole) of cobalt may be reacted with 2 parts (by mole) of a polyisobutene-substituted succinic anhydride at 110-155° C. or 140-150° C. for 5 to 6 hours to provide a cobalt modified dispersant or intermediate. The resulting material (30 g) may be further reacted with a succinimide dispersant from polyisobutene-substituted succinic anhydride and a polyethylenepolyamine mixture (127 g +diluent oil) at 155° C. for 1.5 hours, to produce a cobalt-modified succinimide dispersant.

Dispersants are well known in the field of lubricants and include primarily what is known as ashless-type dispersants and polymeric dispersants. Ashless type dispersants are characterized by a polar group attached to a relatively high molecular weight hydrocarbon chain. Typical ashless dispersants include nitrogen-containing dispersants such as N-substituted long chain alkenyl succinimide, having a variety of chemical structures including typically

where each R¹ is independently an alkyl group, frequently a polyisobutyl group with a molecular weight of 500-5000, and R² are alkylene groups, commonly ethylene (C₂H₄) groups. Such molecules are commonly derived from reaction of an alkenyl acylating agent with a polyamine, and a wide variety of linkages between the two moieties is possible in addition to the representative imide structure shown above, including a variety of amides and ammonium salts. Succinimide dispersants are more fully described in U.S. Pat. Nos. 4,234,435 and 3,172,892.

The invention further provides a method of lubricating an internal combustion engine comprising the step of supplying to the internal combustion engine the lubricating composition described herein.

DETAILED DESCRIPTION OF THE INVENTION

Various preferred features and embodiments will be described below by way of non-limiting illustration.

The amounts of additives present in the lubricating composition disclosed herein are quoted on an oil free basis, i.e., amount of actives, unless otherwise noted.

Oils of Lubricating Viscosity

The lubricating compositions of the invention comprise an oil of lubricating viscosity. Suitable oils include both natural and synthetic oils, oil derived from hydrocracking, hydrogenation, and hydro finishing, unrefined, refined, re-refined oils or mixtures thereof.

Unrefined oils are those obtained directly from a natural or synthetic source generally without (or with little) further purification treatment.

Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Purification techniques are known in the art and include solvent extraction, secondary distillation, acid or base extraction, filtration, percolation and the like.

Re-refined oils are also known as reclaimed or reprocessed oils, and are obtained by processes similar to those used to obtain refined oils and often are additionally processed by techniques directed to removal of spent additives and oil breakdown products.

Natural oils useful in making the inventive lubricants include animal oils, vegetable oils (e.g., castor oil,), mineral lubricating oils such as liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types and oils derived from coal or shale or mixtures thereof.

Synthetic lubricating oils are useful and include hydrocarbon oils such as polymerized, oligomerised, or interpolymerised olefins (e.g., polybutylenes, polypropylenes, propyleneisobutylene copolymers); poly(l-hexenes), poly(1-octenes), trimers or oligomers of 1-decene, e.g., poly(l-decenes), such materials being often referred to as poly a-olefins, and mixtures thereof; alkyl-benzenes (e.g. dodecylbenzenes, tetra-decylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)-benzenes); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls); diphenyl alkanes, alkylated diphenyl alkanes, alkylated diphenyl ethers and alkylated diphenyl sulphides and the derivatives, analogs and homologs thereof or mixtures thereof.

Other synthetic lubricating oils include polyol esters (such as Priolube®3970), diesters, liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, and the diethyl ester of decane phosphonic acid), or polymeric tetrahydrofurans. Synthetic oils may be produced by Fischer-Tropsch reactions and typically may be hydroisomerised Fischer-Tropsch hydrocarbons or waxes. In one embodiment, oils may be prepared by a Fischer-Tropsch gas-to-liquid synthetic procedure as well as other gas-to-liquid oils.

Oils of lubricating viscosity may also be defined as specified in April 2008 version of “Appendix E—API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils”, section 1.3 Sub-heading 1.3. “Base Stock Categories”. In one embodiment, the oil of lubricating viscosity may be an API Group II or Group III oil. In one embodiment, the oil of lubricating viscosity may be an API Group I oil.

The amount of the oil of lubricating viscosity present is typically the balance remaining after subtracting from 100 wt. % the sum of the amount of the compound of the invention and the other performance additives.

The lubricating composition may be in the form of a concentrate and/or a fully formulated lubricant. If the lubricating composition of the invention (comprising the additives disclosed herein) is in the form of a concentrate which may be combined with additional oil to form, in whole or in part, a finished lubricant, the ratio of these additives to the oil of lubricating viscosity and/or to diluent oil include the ranges of 1:99 to 99:1 by weight, or 80:20 to 10:90 by weight.

The Dispersant Treated with Cobalt

The present invention provides a lubricating composition containing an oil of lubricating viscosity and an additive comprising a dispersant treated with cobalt.

In one embodiment, the ashless dispersant reacted with cobalt, hereinafter additive, may be present in a lubricating composition in a concentration from about 0.5 to about 10 weight percent, more desirably from about 1 to about 5 weight percent, and preferably from about 1.5 to about 3.5 weight percent based on the total weight of the lubricating compositions. Desirably the amount of cobalt incorporated into the lubricant from treating the dispersant in the lubricating composition is from about 40 to about 500 parts per million parts by weight (ppm) of lubricating composition, more desirably from about 50, 60 or 70 to about 300 ppm, and in one embodiment from about 80 to 250 ppm. Sources of cobalt include CoCl₂, Co(OH)₂, Co(CO₃), CO(SO₄), CoO, Co₄S₄, Co(NO₃)₂, CoMoO₄, Co₂B, Co₂P, Co(NO₂)₂, and Co(acac)₂.

Generally, the ashless dispersant and the cobalt compound will be reacted together at temperatures of at least 100° C., more desirably at least 140° C. for times such as desirably at least 1 hour and more desirably at least 2 or 4 hours so as to form a reaction product where a significant portion of cobalt is physically or chemically associated with the dispersant. While a reaction product is the desired result, it is acknowledged that some cobalt and some ashless dispersant may remain in the form of reactants that haven't been converted to associated materials.

Suitable dispersants for use in the compositions of the present invention include succinimide dispersants. In one embodiment, the dispersant may be present as a single dispersant. In one embodiment, the dispersant may be present as a mixture of two or three different dispersants, wherein at least one may be a succinimide dispersant.

The succinimide dispersant may be a derivative of an aliphatic polyamine, or mixtures thereof. The aliphatic polyamine may be aliphatic polyamine such as an ethylenepolyamine, a propylenepolyamine, a butylenepolyamine, or mixtures thereof. In one embodiment, the aliphatic polyamine may be ethylenepolyamine. In one embodiment, the aliphatic polyamine may be selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyamine still bottoms, and mixtures thereof.

The dispersant may be a N-substituted long chain alkenyl succinimide. Examples of N-substituted long chain alkenyl succinimide include polyisobutylene succinimide. Typically, the polyisobutylene from which polyisobutylene succinic anhydride is derived has a number average molecular weight of 350 to 5000, or 550 to 3000 or 750 to 2500. Succinimide dispersants and their preparation are disclosed, for instance in U.S. Pat. Nos. 3,172,892; 3,219,666; 3,316,177; 3,340,281; 3,351,552; 3,381,022; 3,433,744; 3,444,170; 3,467,668; 3,501,405; 3,542,680; 3,576,743; 3,632,511; 4,234,435; Re 26,433; 6,165,235; 7,238,650; and EP Patent Application 0 355 895 A.

Another class of ashless dispersant is Mannich base type. These are materials which are formed by the condensation of a higher molecular weight, alkyl-substituted phenol, an alkylene polyamine, and an aldehyde such as formaldehyde. Such materials may have the general structure

(including a variety of isomers and the like) and are described in more detail in U.S. Pat. No. 3,634,515.

Another class of ashless dispersants is high molecular weight ester type. These materials are similar to the above-described succinimides except that they may be seen as having been prepared by reaction of a hydrocarbyl acylating agent and a polyhydric aliphatic alcohol such as glycerol, pentaerythritol, or sorbitol. Such materials are described in more detail in U.S. Pat. No. 3,381,022.

Other dispersants include polymeric dispersant additives, which are generally hydrocarbon-based polymers which contain polar functionality to impart dispersancy characteristics to the polymer.

Dispersants can also be post-treated by reaction with any of a variety of agents. Among these are urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides, boron compounds, and phosphorus compounds. References detailing such treatment are listed in U.S. Pat. Nos. 4,654,403 or 3,306,908.

Additional Performance Additives

The compositions of the invention may optionally comprise one or more additional performance additives. These additional performance additives may include one or more metal deactivators, viscosity modifiers, detergents, friction modifiers, antiwear agents, corrosion inhibitors, dispersants (other than the compound of the present invention), dispersant viscosity modifiers, extreme pressure agents, antioxidants, foam inhibitors, demulsifiers, pour point depressants, seal swelling agents, and any combination or mixture thereof. Typically, fully-formulated lubricating oil will contain one or more of these performance additives, and often a package of multiple performance additives.

In one embodiment, the invention provides a lubricating composition further comprising an antiwear agent, a dispersant viscosity modifier, a friction modifier, a viscosity modifier, an antioxidant, an overbased detergent, or a combination thereof, where each of the additives listed may be a mixture of two or more of that type of additive. In one embodiment, the invention provides a lubricating composition further comprising an antiwear agent, a dispersant viscosity modifier, a friction modifier, a viscosity modifier (typically an olefin copolymer such as an ethylene-propylene copolymer), an antioxidant (including phenolic and/or aminic antioxidants), an overbased detergent (including overbased sulfonates and phenates), or a combination thereof, where each of the additives listed may be a mixture of two or more of that type of additive.

In one embodiment, the lubricating composition of the invention further includes an antiwear agent such as a phosphorus- containing antiwear agent such as a dithiophosphate agent such as a metal dihydrocarbyl dithiophosphate (typically zinc dialkyldithiophosphate (ZDDP)), wherein the metal dihydrocarbyl dithiophosphate contributes at least 100 ppm, at least 200 ppm, at least 250 ppm, 200 ppm to 1000 ppm, or 250 or 300 ppm to 800 ppm, or 300 or 400 ppm to 600 ppm of phosphorus to the lubricating composition. In one embodiment, the lubricating composition is free of or substantially free (meaning less than 100, less than 50 or less than 20 ppm of phosphorus from a metal dialkyldithiophosphate such as zinc dialkyldithiophosphate).

In one embodiment, the lubricating composition of the invention further comprises a dispersant viscosity modifier. The dispersant viscosity modifier may be present at 0 wt. % to 5 wt. %, 0 wt. % to 4 wt. %, or 0.05 wt. % to 2 wt. % of the lubricating composition.

Suitable dispersant viscosity modifiers include functionalized polyolefins, for example, ethylene-propylene copolymers that have been functionalized with an acylating agent such as maleic anhydride and an amine; polymethacrylates functionalized with an amine, or esterified styrene-maleic anhydride copolymers reacted with an amine. More detailed description of dispersant viscosity modifiers are disclosed in International Publication WO2006/015130 or U.S. Pat. Nos. 4,863,623; 6,107,257; 6,107,258; and 6,117,825.

In one embodiment, the dispersant viscosity modifier may include those described in U.S. Pat. No. 4,863,623 (see column 2, line 15 to column 3, line 52) or in International Publication WO2006/015130 (see page 2, paragraph [0008] and preparative examples are described paragraphs [0065] to [0073]).

In one embodiment it is desirable if the lubricant composition has low level or is free of metals selected from the group of molybdenum, titanium, and boron. In one embodiment the lubricant composition has less than 100, less than 50, less than 20, less than 20 or 0 ppm of molybdenum based on the weight of the lubricant composition. Ppm is an abbreviation for parts by weight per million parts by weight of the total composition. In one embodiment the lubricant composition has less than 50, less than 30, less than 10, less than 5 or 0 ppm of titanium based on the weight of the lubricant composition. In one embodiment the lubricant composition has less than 100, less than 80, less than 50, less than 25, less than 10, or 0 ppm of boron based on the weight of the lubricant composition. In one embodiment the limitations on molybdenum, titanium, and boron are all together applied to the composition

In one embodiment, the invention provides a lubricating composition further comprising an overbased detergent. The overbased detergent may be selected from the group consisting of sulfur-free phenates, sulfur-containing phenates, sulfonates, salixarates, salicylates, and mixtures thereof.

The overbased detergent may also include “hybrid” detergents formed with mixed surfactant systems including phenate and/or sulfonate components, e.g., phenate/salicylates, sulfonate/phenates, sulfonate/salicylates, sulfonates/phenates/salicylates, as described for example, in U.S. Pat. Nos. 6,429,178; 6,429,179; 6,153,565; and 6,281,179. Where, for example, a hybrid sulfonate/phenate detergent is employed, the hybrid detergent would be considered equivalent to amounts of distinct phenate and sulfonate detergents introducing like amounts of phenate and sulfonate soaps, respectively.

Typically, an overbased detergent may be sodium salts, calcium salts, magnesium salts, or mixtures thereof of the phenates, sulfur containing phenates, sulfonates, salixarates and salicylates. Overbased phenates and salicylates typically have a total base number of 180 to 450 TBN. Overbased sulfonates typically have a total base number of 250 to 600, or 300 to 500. Overbased detergents are known in the art. In one embodiment, the sulfonate detergent may be predominantly a linear alkylbenzene sulfonate detergent having a metal ratio of at least 8 as is described in paragraphs [0026] to [0037] of US Patent Publication 2005065045 (and granted as U.S. Pat. No. 7,407,919). The linear alkylbenzene sulfonate detergent may be particularly useful for assisting in improving fuel economy. The linear alkyl group may be attached to the benzene ring anywhere along the linear chain of the alkyl group, but often in the 2-, 3- or 4- position of the linear chain. In some instances, the linear alkyl group may be attached predominantly in the 2- position, resulting in the linear alkylbenzene sulfonate detergent. The overbased detergent may be present at 0 wt. % to 15 wt. %, 0.1 wt. % to 10 wt. %, 0.2 wt. % to 8 wt. %, or 0.2 wt. % to 3 wt. %. For example, in a heavy duty diesel engine the detergent may be present at or 2 wt. % to 3 wt. % of the lubricating composition. For a passenger car engine the detergent may be present at 0.2 wt. % to 1 wt. % of the lubricating composition.

In one embodiment, the lubricating composition includes an antioxidant, or mixtures thereof. The antioxidant may be present at 0 wt. % to 15 wt. %, 0.1 wt. % to 10 wt. %, or 0.5 wt. % to 5 wt. % of the lubricating composition.

Antioxidants include sulfurized olefins, alkylated diarylamines (typically alkylated phenyl naphthyl amines, for example those commercially available as Irganox® L 06 from CIBA, or alkylated diphenylamines such as dinonyl diphenylamine, octyl diphenylamine, dioctyl diphenylamine), hindered phenols, molybdenum compounds (such as molybdenum dithiocarbamates), or mixtures thereof.

The hindered phenol antioxidant often contains a secondary butyl and/or a tertiary butyl group as a sterically hindering group. The phenol group may be further substituted with a hydrocarbyl group (typically linear or branched alkyl) and/or a bridging group linking to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol or 4-butyl-2,6-di-tert-butylphenol, or 4-dodecyl-2,6-di-tert-butylphenol. In one embodiment, the hindered phenol antioxidant may be an ester and may include e.g., Irganox™ L-135 from Ciba. A more detailed description of suitable ester-containing hindered phenol antioxidant chemistry is found in U.S. Pat. No. 6,559,105.

Examples of friction modifiers include long chain fatty acid derivatives of amines, fatty esters, or epoxides; fatty imidazolines such as condensation products of carboxylic acids and polyalkylene-polyamines; amine salts of alkylphosphoric acids; fatty alkyl tartrates; fatty alkyl tartrimides; or fatty alkyl tartramides. In some embodiments, the term fatty, as used herein, can mean having a C8-22 linear alkyl group.

Friction modifiers may also encompass materials such as sulfurised fatty compounds and olefins, molybdenum dialkyldithiophosphates, molybdenum dithiocarbamates, sunflower oil or monoester of a polyol and an aliphatic carboxylic acid.

In one embodiment, the friction modifier may be selected from the group consisting of long chain fatty acid derivatives of amines, long chain fatty esters, or long chain fatty epoxides; fatty imidazolines; amine salts of alkylphosphoric acids; fatty alkyl tartrates; fatty alkyl tartrimides; and fatty alkyl tartramides. The friction modifier may be present at 0 wt. % to 6 wt. %, 0.05 wt. % to 4 wt. %, or 0.1 wt. % to 2 wt. % of the lubricating composition.

In one embodiment, the friction modifier may be a long chain fatty acid ester. In another embodiment, the long chain fatty acid ester may be a monoester or a diester or a mixture thereof, and in another embodiment, the long chain fatty acid ester may be a triglyceride.

Other performance additives such as corrosion inhibitors include those described in paragraphs 5 to 8 of US Application US05/038319, published as WO2006/047486, octyl octanamide, condensation products of dodecenyl succinic acid or anhydride and a fatty acid such as oleic acid with a polyamine. In one embodiment, the corrosion inhibitors include the Synalox® corrosion inhibitor. The Synalox® corrosion inhibitor may be a homopolymer or copolymer of propylene oxide. The Synalox® corrosion inhibitor is described in more detail in a product brochure with Form No. 118-01453-0702 AMS, published by The Dow Chemical Company. The product brochure is entitled “SYNALOX Lubricants, High-Performance Polyglycols for Demanding Applications.”

Metal deactivators including derivatives of benzotriazoles (typically tolyltriazole), dimercaptothiadiazole derivatives, 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, or 2-alkyldithiobenzothiazoles; foam inhibitors including copolymers of ethyl acrylate and 2-ethylhexyl acrylate and copolymers of ethyl acrylate and 2-ethylhexylacrylate and vinyl acetate; demulsifiers including trialkyl phosphates, polyethylene glycols, polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers; pour point depressants including esters of maleic anhydride-styrene, polymethacrylates, polyacrylates or polyacrylamides may be useful.

Pour point depressants that may be useful in the compositions of the invention include poly(alphaolefins), esters of maleic anhydride-styrene, poly(meth)acrylates, polyacrylates or polyacrylamides.

In different embodiments, the lubricating composition may have a composition as described in the following Table 1:

TABLE 1 Embodiments (wt. %) Additive A B C Additive of Invention, dispersant 0.5 to 10  1 to 6   1.5 to 3.5 treated with cobalt Dispersant Viscosity Modifier 0 or 0.05 to 5  0 or 0.05 to 4 0.05 to 2  Overbased Detergent 0 or 0.05 to 15 0.1 to 10 0.2 to 8 Antioxidant aminic and/or 0 or 0.05 to 15 0.1 to 10 0.5 to 5 phenolic Antiwear Agent, e.g. 0 or 0.05 to 15 0.1 to 10 0.3 to 5 dithiophosphate Friction Modifier 0 or 0.05 to 6  0.05 to 4  0.1 to 2 Viscosity Modifier 0 or 0.05 to 10 0.5 to 8    1 to 6 Any Other Performance Additive 0 or 0.05 to 10 0 or 0.05 to 8 0 or 0.05 to 6 Oil of Lubricating Viscosity Balance to 100 Balance to 100 Balance to 100

The present invention provides a surprising ability to reduce high temperature deposit formation on walls of the reactor in the KHT test simply by modifying the dispersant with a few hundred ppm of cobalt.

INDUSTRIAL APPLICATION

In one embodiment, the invention provides a method of lubricating an internal combustion engine comprising the step of supplying to the internal combustion engine a lubricating composition as disclosed herein. Generally the lubricant is added to the lubricating system of the internal combustion engine, which then delivers the lubricating composition to the critical parts of the engine that require lubrication during its operation,.

The lubricating compositions described above may be utilized in an internal combustion engine. The engine components may have a surface of steel or aluminum (typically a surface of steel), and may also be coated for example with a diamond like carbon (DLC) coating.

An aluminum surface may be comprised of an aluminum alloy that may be a eutectic or hyper-eutectic aluminum alloy (such as those derived from aluminum silicates, aluminum oxides, or other ceramic materials). The aluminum surface may be present on a cylinder bore, cylinder block, or piston ring having an aluminum alloy, or aluminum composite.

The internal combustion engine may or may not have an Exhaust Gas Recirculation (ERG) system. The internal combustion engine may be fitted with an emission control system or a turbocharger. Examples of the emission control system include diesel particulate filters (DPF), or systems employing selective catalytic reduction (SCR).

In one embodiment, the internal combustion engine may be a diesel fuelled or biofuelled engine (typically a heavy duty diesel engine), a gasoline fuelled engine, a natural gas fuelled engine or a mixed gasoline/alcohol fuelled engine. In one embodiment, the internal combustion engine may be a diesel fuelled engine and in another embodiment, a gasoline fuelled engine.

The internal combustion engine may be a 2-stroke or 4-stroke engine. Suitable internal combustion engines include marine diesel engines, aviation piston engines, low-load diesel engines, and automobile and truck engines.

The internal combustion engine of the present invention is distinct from gas turbine. In an internal combustion engine, individual combustion events which through the rod and crankshaft translate from a linear reciprocating force into a rotational torque. In contrast, in a gas turbine (may also be referred to as a jet engine) it is a continuous combustion process that generates a rotational torque continuously without translation and can also develop thrust at the exhaust outlet. These differences result in the operation conditions of a gas turbine and internal combustion engine different operating environments and stresses.

The lubricant composition for an internal combustion engine may be suitable for any engine lubricant irrespective of the sulfur, phosphorus or sulfated ash (ASTM D-874) content. The sulfur content of the engine oil lubricant may be 1 wt. % or less, 0.8 wt. % or less, 0.5 wt. % or less, or 0.3 wt. % or less. In one embodiment, the sulfur content may be in the range of 0.001 wt. % to 0.5 wt. % or 0.01 wt. % to 0.3 wt. %. The phosphorus content may be 0.2 wt. % or less, 0.12 wt. % or less, 0.1 wt. % or less, 0.085 wt. % or less, 0.08 wt. % or less, even 0.06 wt. % or less, 0.055 wt. % or less, or 0.05 wt. % or less. In one embodiment, the phosphorus content may be 100 ppm to 1000 ppm, or 200 ppm to 600 ppm. The total sulfated ash content may be 2 wt. % or less, 1.5 wt. % or less, 1.1 wt. % or less, 1 wt. % or less, 0.8 wt. % or less, 0.5 wt. % or less, or 0.4 wt. % or less. In one embodiment, the sulfated ash content may be 0.05 wt. % to 0.9 wt. %, 0.1 wt. % to 0.2 wt. % or to 0.45 wt. %. Desirably in one embodiment, the amount of sulfur from all the sulfur containing additives is from about 500 or 1000 to about 2500 ppm sulfur, based on the weight of the lubricant compositions, more desirably from about 500 to about 1500 ppm.

In one embodiment, the lubricating composition may be an engine oil, wherein the lubricating composition may be characterized as having at least one of (i) a sulfur content of 0.5 wt. % or less, (ii) a phosphorus content of 0.1 wt. % or less, (iii) a sulfated ash content of 1.5 wt. % or less, or combinations thereof.

EXAMPLES

The invention will be further illustrated by the following examples, which set forth particularly advantageous embodiments. While the examples are provided to illustrate the invention, they are not intended to limit it.

Comparative Example 1 (CEX1): Synthesis of Succinimide Dispersant from 2000 Mn Conventional Polyisobutylene

A 2 L 4-necked round bottom flask was equipped with a stirrer, dropping funnel, sub-surface tube, thermowell, Dean-Stark trap and Friedrick's condenser, charged with polyisobutylene succinic anhydride (550 g, 2000 Mn, conventional PIBSA, TAN=68), diluent oil (505 g) and purged with nitrogen. Polyethylene amine still bottoms (25 g, 34 wt. % N) were added to the dropping funnel. The mixture was warmed to 110° C. with stirring. The polyamine was added drop-wise to the sub-surface tube over 35 min. The temperature was increased to 155° C. and the preparation was stirred for 5.25 h. 2.2 g water was collected in the Dean-Stark trap. Diatomaceous earth (16 g) was added to the mixture and the dispersant was filtered through a supplemental pad of diatomaceous earth (16 g) to yield a succinimide dispersant as a clear brown oil (1013 g, KV100=548, % N=0.79).

Comparative Example 2 (CEX2): Synthesis of Al-Containing Dispersant

The dispersant of Comparative Example 1 (1400 g) is charged to a 2 L 4-necked round bottom flask equipped with a stirrer, thermowell, sub-surface tube, Dean-Stark trap and Friedrick's condenser and the flask was purged with nitrogen. The dispersant was warmed to 90° C. with stirring. Al(PrO)₃ (45 g) was charged in one aliquot and the temperature was increased to 155° C. The mixture was stirred for 5 h, filtered through diatomaceous earth and cooled to yield a brown oil (1375 g, KV100=4626 cSt, 0.27% Al).

Comparative Example 3 (CEX3): Synthesis of La-Containing Dispersant

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 1 (1300 g) was treated with La(OH)₃ (7.1 g) to yield a brown oil (1178 g, KV100=487 cSt).

Comparative Example 4 (CEX4): Synthesis of Ba-Containing Dispersant

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 1 (1300 g) was treated with Ba(OH)₂.8H₂O (12 g) to yield a brown oil (1187 g, KV100=478 cSt, 0.38% Ba).

Comparative Example 5 (CEXS): Synthesis of Zn-Containing Dispersant

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 1 (1300 g) was treated with Zn(OAc)₂ (18 g) to yield a brown oil (1216 g, KV100=682 cSt, 0.39% Zn).

Example 6 (EX6): Synthesis of Co-Containing Dispersant from Co(CO3)

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 1 (1200 g) was treated with CoCO₃ (11.4 g) to yield a brown oil (1082 g, KV100=650 cSt).

Example 7 (EX7): Synthesis of Co-Containing Dispersant from CoCl₂

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 1 (1200 g) was treated with CoCl₂.6H₂O (22.7 g) to yield a brown oil (1054 g, KV100=1090 cSt).

Example 8 (EX8): Synthesis of Co-Containing Dispersant from Co(OH)₂

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 1 (1200 g) was treated with Co(OH)₂ (8.9 g) to yield a brown oil (981 g, KV100 =618 cSt).

Example 9 (EX9): Synthesis of Co-Containing Dispersant from Co(acac)₂(100%)

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 1 (1200 g) was treated with Co(acac)₂ (24.6 g) to yield a brown oil (1092 g, KV100=863 cSt).

Preparative Example 10 (PEX10): Synthesis of High TBN Succinimide Dispersant from 2000 Mn Conventional Polyisobutylene

A 2 L 4-necked round bottom flask was equipped with a stirrer, dropping funnel, sub-surface tube, thermowell, Dean-Stark trap and Friedrick's condenser, charged with polyisobutylene succinic anhydride (600 g, 2000 Mn, conventional PIBSA, TAN=73), diluent oil (635 g) and purged with nitrogen. Polyethylene amine still bottoms (43 g, 34 wt. % N) were added to the dropping funnel. The mixture was warmed to 110° C. with stirring. The polyamine was added drop-wise to the sub-surface tube over 35 min. The temperature was increased to 155° C. and the preparation was stirred for 5.25 h. 3.1 g water was collected in the Dean-Stark trap. Diatomaceous earth (18 g) was added to the mixture and the dispersant was filtered through a supplemental pad of diatomaceous earth (18 g) to yield a succinimide dispersant as a clear brown oil (1117 g, KV100=183, %N =1.2).

Example 11 (EX11): Synthesis of Co-Containing Dispersant from Co(acac)₂(100%)

The procedure of Comparative Example 2 was used except the dispersant of Comparative Example 10 (1200 g) was treated with Co(acac)₂ (23.2 g) to yield a brown oil (1068 g, KV100 =232 cSt).

Lubricating Oils:

The materials from Examples 1-11 were blended into an API SN capable lubricating oil (5W-30) in group II basestocks as detailed in Table 2. Component descriptions and treat rates are listed on a diluent oil free basis.

-   Comparative Lubricant 1 (CL1) contains Comparative Dispersant     Example 1 which is a baseline that contains no succinimide     dispersant post-treatment with a metal. -   Comparative Lubricants 2-5 (CL2-CL5) contain equivalent treat rates     of Comparative Dispersant Examples 2-5 containing Al, La, Ba and Zn     post-treatments, respectively. These metals have only one stable     oxidation state. -   Lubricants L6 through L9 and L11 contain equivalent treat rates of     Dispersant Examples 6-9 and 11 (EX6-EX9 and EX11).

TABLE 2 Formulas Tested (Treat Rates on Oil Free Basis) Lubricant # CL1 CL2 CL3 CL4 CL5 L6 L7 L8 L9 L11 Dispersant CEX1 CEX2 CEX3 CEX4 CEX5 EX6 EX7 EX8 EX9 EX11 Disp. Treat 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 2.12 Group II Oil BALANCE to 100 g Ca Sulfonate¹ 0.74 g Na Sulfonate² 0.17 AO³ 2.16 ZDP⁴ 0.79 VI Improver⁵ 0.7 Other⁶ 0.2 Disp Metal — Al La Ba Zn Co Co Co Co Co % M (ppm) 0 160 150 150 155 188 188 188 188 188 ¹Combination of 520 TBN and 690 TBN overbased calcium sulfonate detergents ²Overbased sodium sulfonate detergent (650 TBN) ³C3/C6 secondary zinc dialkyldithiophosphate (ZDDP) ⁴Combination of hindered phenol, alkylated diphenyl amine, and sulfurized olefin ⁵Ethylene-propylene copolymer ⁶Other additives include friction modifier(s), foam inhibitor(s), and/or pour point depressant(s)

Performance Testing:

The Lubricants from Table 1 were tested in the KHT test. Briefly, 5 mL of the test oil was pumped through a heated glass capillary tube at 0.31 cc/h. The sample was purged with air at a rate of 10 cc/min. The sample was circulated through the glass tube for 16 h while the tube is heated to 280° C. At the end of test, the tube is visually rated according to the scale found in FIG. 1 (10 =clean tube, 0=dirty tube).

Table 3 shows the KHT performance of the Lubricants from Table 2. The comparative lubricants (CL1-CL5) all gave dirty black tubes (0) while the inventive lubricants (6-9) all gave much cleaner tubes in the range of about 9.

TABLE 3 KHT Performance of the Lubricants from Table 1 Lubricant CL1 CL2 Cl3 CL4 CL5 L6 L7 L8 L9 KHT Rating 0 0 0 0 0 9 9 9 9

It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may be different from those that are initially added. The products formed thereby, including the products formed upon employing lubricant composition of the present invention in its intended use, may not be susceptible of easy description. Nevertheless, all such modifications and reaction products are included within the scope of the present invention; the present invention encompasses lubricant compositions prepared by admixing the components described above.

Each of the documents referred to above is incorporated herein by reference, as is the priority document and all related applications, if any, which this application claims the benefit of. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word “about.” Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical component is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, unless otherwise indicated. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention may be used together with ranges or amounts for any of the other elements.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character.

Examples of hydrocarbyl groups include:

-   (i) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or     alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents,     and aromatic-, aliphatic-, and alicyclic-substituted aromatic     substituents, as well as cyclic substituents wherein the ring is     completed through another portion of the molecule (e.g., two     substituents together form a ring); -   (ii) substituted hydrocarbon substituents, that is, substituents     containing non-hydrocarbon groups which, in the context of this     invention, do not alter the predominantly hydrocarbon nature of the     substituent (e.g., halo (especially chloro and fluoro), hydroxy,     alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulphoxy); -   (iii) hetero substituents, that is, substituents which, while having     a predominantly hydrocarbon character, in the context of this     invention, contain other than carbon in a ring or chain otherwise     composed of carbon atoms.

Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocarbyl group.

While the invention has been explained in relation to its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims. 

What is claimed:
 1. An internal combustion engine lubricant composition comprising; a) an oil of lubricating viscosity, b) about 0.5 to 10 wt. % of a metal substituted dispersant based on the weight of said engine oil lubricant composition, c) an antioxidant, d) an antiwear additive, wherein the metal of the metal dispersant comprises cobalt and the amount of metal substituted dispersant is such to provide about 40 to 500 ppm of cobalt to said engine lubricant composition and wherein the lubricant composition comprises sulfur in an amount of less than 1 wt. % and phosphorus in an amount of less than 0.2 wt. % based on the weight of said lubricant composition.
 2. A composition according to claim 1, wherein said metal substituted dispersant is present from about 1 to about 6 wt. % of said lubricant composition.
 3. A composition according to claim 1, wherein said cobalt is present from about 50 to about 300 ppm in said engine lubricant composition.
 4. A composition according to claim 1, wherein said cobalt is present from about 80 to about 250 ppm in said engine lubricant composition.
 5. A composition according to claim 1, wherein said metal substituted dispersant is present from about 1.5 to about 3.5 wt. % in said engine lubricant composition.
 6. A composition according to claim 1, wherein said metal substituted dispersant is a metal substituted succinimide dispersant.
 7. A composition according to claim 1, further comprising an overbased detergent.
 8. A composition according to claim 1, wherein said antioxidant comprises an aminic antioxidant and/or a phenolic antioxidant.
 9. A composition according to claim 8, wherein said aminic antioxidant is present in an amount from about 0.1 to about 10 wt. % based on said lubricant composition.
 10. A composition according to claim 8, wherein said phenolic antioxidant is present in an amount from about 0.1 to about 10 wt. % based on said lubricant composition.
 11. A composition according to any of claim 1, wherein said anti-wear agent is a metal dithiophosphate antiwear agent.
 12. A composition according to claim 1, wherein the lubricant composition comprises sulfur in an amount of less than 0.8 wt. % and phosphorus in an amount of less than 0.1 wt. % based on the weight of said lubricant composition.
 13. A composition according to claim 1, wherein the lubricant composition comprises molybdenum in an amount of less than 100 parts per million parts in weight/weight (ppm), and boron in the amount of less than 100 ppm, all based on the weight of the lubricant composition.
 14. A method of using an ashless dispersant reacted with a cobalt compound as an additive in a lubricating composition to reduce engine deposits when said lubricant is exposed to use at temperatures of 150° C. or more and wherein said ashless dispersant reacted with a cobalt compound is used in an amount to provide about 40 to 500 ppm of cobalt to said lubricating composition and wherein the lubricating composition comprises sulfur in an amount of less than 1 wt. % and phosphorus in an amount of less than 0.2 wt. % based on the weight of said lubricating composition.
 15. A method of using an ashless dispersant according to claim 4, wherein said lubricant is exposed to use at temperatures of 200° C. or more. 